Telephone system



Jan. 7, 19 36. Q. MYERS 2,027,194

TELEPHONE SYSTEM 7 Filed July 20, 1934 70 SNDER ADWNCE SELECTOR SENOER mmw ' INVENTOR 0- MYERS BY A T TORNE? UNITED STATES PATENT OFFICE 2,027,194 TELEPHONE SYSTEM Oscar Myers, Brooklyn,

Telephone Laboratories,

N. Y., assignor to Bell Incorporated, New

York, N. Y., a corporation of New York Application July 20, 1934, Serial No. 736,144

6 Claims.

This invention relates to telephone systems and more particularly to the utilization in the impulse recording circuits thereof of gaseous discharge or conductor tubes as impulse responsive relays.

In a machine switching telephone system of the type employing a common sender which controls the setting of selector switches, the sender is provided with registers which are set by a series of impulses dialed by a subscriber in accordance with the directory number of a desired line. If the sender is employed in a telephone system of the type employing power driven selector switches, for example of the panel type, the setting of the switches is controlled in accordance with the setting of the sender registers by impulses transmitted revertively to the sender by the switches during their selective movement. The control circuit, known as the fundamental circuit, has heretofore comprised a control relay in the selector at the time associated with the sender and an impulse responsive or stepping relay in the sender.

When the control circuit is established preparatory to setting the switch both relays operate by battery and ground usually applied at the switch to the two conductors respectively of the fundamental circuit. The operation of the control relay at the switch starts the movement of the brush shaft of the switch and the impulse relay at the sender prepares the sender for controlling movement of the brush the amount of selective shaft of the switch.' The switch is provided with a commutator which, as the brush shaft advances, intermittently connects ground to one of the conductors of the control circuit thereby intermittently shunting the impulse relay of the sender. The intermittent operation of the impulse relay controls the successive operations of relays of a train of counting relays, the end relay of the train when operated opening the control circuit to movement of the brush arrest further shaft of the switch. The

number of counting relays operated by the impulse relay to control the amount of selective movement of the switch is determined by the setting of the register of rendered effective.

the sender at the time The present invention provides for the replacement of the usual impulse responsive or stepping relay of the control or fundamental circuit by a gaseous conductor or discharge tube. The gaseous conductor tube utilized is a tube filled with a low pressure gaseous poses of lium, mercury vapor or this group. The tube content which, for purillustration, might be neon, argon, hecombinations of gases of has a certain characteristic, namely, that the gaseous content will become ionized and thus conducting on one potential determined by the electrode design, the nature of the gaseous content and its pressure but once rendered conducting will remain in this condition of conductivity on a much lower potential.

The invention has for its object the utilization of a gaseous conductorftube as an impulse responive relay whereby more accurate and faster i0 impulse control may be realized over long fundamental circuits loops. 7

The present invention has been illustrated schematically by only so much of a sender circuit and a selector switch circuit as are necessary to a complete understanding of the invention.

A typical sender, circuit to which the invention is applicable is disclosed in detail in Patent No. 1,862,549 granted June 14, 1932 to R. Raymond et al. A typical selector switch circuit is disclosed in detail in Patent No. 1,395,977 granted to F. A. Stearn et al on November 1, 1921.

In the application of the invention to the revertive control of a selector switch, the fundamental or co'ntrol circuit is established in the well known manner between the sender and the selector switch to be controlled, the control relay of the switch operating and looking over the fundamental circuit and closing the circuit of the up-drive magnet of the switch. At the sender, the fundamental circuit is looped through the primary winding of a transformer, the secondary winding of which is connected in a circuit from the negative or ungrounded terminal of the central station battery to the grid of a gaseous dis- 5 charge tube. The grid of the tube is thus normally negatively biased preventing the ionization of the tube. The anode of the tube is connected to the winding of one of a train of counting relays through contacts of the relays of a particular register then effective for controlling the selective movement of the switch, to the positive terminal of the central station battery.

As the brush shaft of the selector switch advances under the control of the up-drive magnet, ground is connected to the tip conductor of the fundamental circuit and the primary winding of the transformer becomes short-circuited thereby causing a surge of potential in the secondary winding of the transformer of such polarity as to make the grid less negative. The tube thereupon ionizes and becomes conducting. The particular counting relay connected to the anode circuit of the tube now operates, locking itself operated, shunting the anode circuit momen- 'until the tube reionizes when the commutator again connects ground to the tip conductor of the fundamental circuit. Thus, as the commutator intermittently connects ground to the tip conductor of the fundamental circuit, the tube causes.

successive counting relays to operate until the end relay operates to open the fundamental circuit and to prepare the sender-for the next selection control.

Since the tube ionizes very rapidly when its grid is made sufiiciently less negative, a very short application of ground to the tip conductor of the fundamental circuit by the switch commutator is eifective to cause the tube to ionize and become conducting and therefore the speed at which the switch shaft may be advanced may be materially increased o'ver the speed hitherto possible. Further, in view of the fact that the tube responds to successive closures of the switch commutator as contrasted with the present fundamental circuit employing an impulse responsive relay which controls the counting relays in response to successive closures and openings of the switch commutator, it is possible to use a train of counting relays having fewer relays than heretofore employed and relays of a simpler and more reliable type.

' The invention will be more clearly understood by reference to the accompanying drawing. The apparatus shown to the right of the dotted line ABCD represents schematically in part the apparatus of a selector circuit of the panel type. Since this is well known in the art, only those parts which are necessary for an understandingof the invention are shown. Omitted parts are represented by dotted lines. The drawing to the left of the line ABCD shows apparatus arranged in accordance with this invention, and is a part of a panel type sender circuit. Only those parts necessary for an understanding of the invention are shown. The apparatus schematically illustrated includes a chain of counting relays 0-9, register relays I %I3, a gaseous discharge tube I d, a stepping relay I9, transformer l5, cathode biasing resistance 26 and 27 and a resistance I8 connected across the fundamental circuit. The sender and selector circuits are connected over the fundamental circuit by conductors represented by the dotted lines 30 and SI.

A detailed description of the operation of the arrangement shown in the drawing will now be given. When the fundamental or control circuit is established in the usual manner, between the sender and selector circuit to be controlled, a circuit through selector control relay 20 may be traced from the negative battery terminal through its winding, over the lower contacts of sequence switch cam 32 and conductor 3@, thence over conductor 48 through either the primary winding ll of transformer I5 and non-inductive resistance I8 (which is used to minimize the effect of electrostatic line capacity) in multiple, or over conductor 38 through the winding of relay I9, depending on the optional use of relay I9, the purpose of which will be hereinafter explained. For the present, it is assumed that only transformer I5 is used and accordingly the circuit being traced, continues over conductors GI and 42 and through normal contacts of relay 9 over conductor 3i to positive gro'und 34 at the selector. Relay 29 operates and locks through its righthand contacts over the circuit just traced.

The functioning of gaseous discharge tube I4 will now be described. Current flows from positive ground through resistances 21 and 26 to the negative terminal of the central office battery. The cathode element of tube It is connected to junction 29, thereby placing said cathode element at a potential intermediate between that of the 10 positive and negative terminals of the battery. The grid elements of tube It is connected to the negative terminal of the central ofiice battery through the secondary winding I6 of transformer I5, thereby maintaining said grid at negativel battery potential, and giving it a negative bias with respect to the catho'de element.

When current passed through the primary winding I! of transformer I5 in connection with the operation of relay 2B, hereinbefore described, a potential was momentarily induced in secondary winding I6 due to the build-up of current in said primary winding. The-windings of transformer I5 are so connected that the said induced potential is added to the potential of the central 25 ofiice battery, resulting in an increase of the negative bias of the grid element of tube I4. Consequently, no current can flow through the circuit of the anode element as a result of the build-up of current through winding I'I, just de- 3 scribed. When relay 20 operated, it closed through its left-hand contacts an obvious circuit through the winding of up-drive magnet 2 I, causing thereby the upward movement of selector commutator brush 22 over commutator 35.

When brush 22 contacts commutator segment 2?, positive ground is connected over brush 22, seg ment 23, right-hand contacts of sequence switch cam 32, to conductor 30 of the fundamental circuit. This short-circuits the circuit over con- 40 ductor 30 through winding I! of transformer I5, which was previously traced, causing the cessation of current in said winding I! and inducing a momentary potential in secondary winding I6 in a direction opposite to that induced when current was established through relay 20. This results in a momentary reduction of the negative bias of the grid element of tube I4, causing the ionization of tube I I and a flow of current through the circuit of its anode element, which circuit will now be traced.

Assuming that register relay II has been previously operated under control of dial impulses in the usual manner, the anode element of tube I4 is connected over conductor 28, through the back contact and winding of counting relay I, left front contact of register relay II, and back contact of register relay It to positve ground. Current now flows over the circuit just traced from the anode element of tube I4, through tube M to its cathode element, thence through resistance 26 to grounded negative battery. Relay I operates and locks through its right-hand front contact to negative battery and also shunts momentarily with negative battery through its back contact the anode circuit of tube I 4, deionizing it. The right-hand front contact of relay I is arranged so that it closes before the back contact breaks, thereby assuring a continuous circuit through the winding of relay 1. closes a circuit through its left-hand front contact from positive ground 33 through the winding and back contact of relay 8 to the anode element of tube M. The left-hand front contact of relay 1 is arranged so that it can not close before the 75 Relay I also right-hand front contact closes, thereby assuring the deionization of tube I4 before the winding of relay 8 is connected, avoiding thereby the false operation of relay 8 on the pulse that operated relay I.

As the advancing selector brush 22 contacts the next insulated segment of comutator 35, current again flows over the fundamental circuit through the winding 11 of transformer l5, thereby inducing potential in the winding it due to the build-up of current in the winding I1. This induced potential is added to the potential of the central oflice battery, resulting in an increase of the negative bias on the grid element of tube l4 and consequently no current can flow over the cathode-anode circuit of the tube. When the brush 22 contacts the next commutator segment 24, positive ground is connected over brush 22, segment 24, right-hand contacts of sequence switch cam 32, to conductor 30 of the fundamental circuit. This short-circuits the circuit over conductor 39 through winding I! of transformer l5, which was previously traced, causing thereby the cessation of current in winding IT.

This induces a potential in secondary winding l6 which opposes the potential of the central ofiice battery connected to the grid element of tube l4, thereby reducting the negative bias of said grid and causing tube M to again ionize. As a result of this ionization, current now flows in the anode circuit of tube l4 over a circuit that may be traced from positive ground 33, through left-hand make contacts of relay I, winding and back contact of relay 8, over conductor 28, anode element of tube I4, through tube I4 to its cathode element, through resistance 26 to negative grounded battery. Relay 8 operates and locks on negative battery through the right-hand make contact and winding of relay 8 and left-hand make contact of relay 1 to positive ground 33. The right-hand front contact of relay 8 is arranged so that it closes before the back contact breaks thereby assuring a continuous circuit through the winding of relay 8. Relay 8, in operating, shunts momentarily with negative battery through its back contact, the circuit of the anode element through the winding of relay 8, which was previously traced, deionizing tube 14, and connects through its. left-hand front contact, the winding of counting relay 9 in series with the anode of tube l4 through a circuit which will hereinafter be traced. The left-hand contact of relay 8 is arranged to close after the right-hand front contact, thereby assuring the deionization of tube l4 before the winding of relay 9 is connected.

As the advancing selector brush 22 contacts the next insulated segment of commutator 35, current again flows over the fundamental circuit through the winding ll of transformer l5 thereby inducing potential in the winding l6 due to the build-up of current in winding I1. This induced potential causes an increase of the negative bias on the grid of tube l4 and consequently no current can flow over the cathode-anode circuit of the tube. When the brush 22 contacts the next commutator segment 25, positive ground is connected over brush 22, segment 25, righthand contacts of sequence switch cam 32, to conductor 30, through winding [1 of transformer l5, over the circuit which was previously traced, causing thereby the cessation of current in said winding l'l. This induces a potential in secondary winding it which opposes the potential of the central office battery connected to the grid element of tube l4, thereby reducing the negative bias of said grid and causing tube [4 to again ionize. As a result of this ionization, current now flows in the anode circuit of tube l4 over a circuit that may be traced from positive ground 33, through the left-hand make contacts of relay 8, 5 back contact of relay I3, winding of relay 9, conductor 28, anode element of tube l4, through the tube to the cathode element thereof, resistance 26 to negative terminal of the central office battery. Relay 9 operates and opens the fundamen- 1o tal circuit over its back contact disconnecting the ground 34 to which relay 29 was locked, over a circuit hereinbefore traced.

As selector brush 22 advances past conducting commutator segment 25, it opens the circuit from 15 ground over brush 22, segment 25, upper contact and lower right and left-hand contacts of sequence switch cam 32, to the front contact and winding of selector control relay 20 and the tip of the fundamental circuit, releasing relay 2U. 20

Relay 20 releasing, opens the circuit from ground over its left front contact to negative battery through the winding of selector up-drive magnet 2|, causing magnet 2| to deenergize and arrest the upward movement of the selector brush shaft 25 and brush 22, as the sender counting relays have now been satisfied by the revertive ground pulses from the commutator of the particular selector under control of the sender at this time.

The operation of counting relay 9 also connects 30 ground over its left-hand front contact to lead 43 to cause the sender to advance out of the control position of the selection just completed. The said left-hand front contact of relay 9 is arranged to close after the back contact of relay 9 35 opens,thereby assuring the delay of the sender advance until the upward movement of the selector brush shaft is arrested as hereinbefore explained. The advance of the sender circuit disconnects the negative battery from the windings of the count- 40 ing relays I and 8 which are being held operated. These relays now release. Relay 8 in releasing, opens its left-hand front contact, releasing relay 9 and opening the circuit through the winding of relay 9 and the anode element of tube l4, deioniz- 4.5 ing tube I4. All counting relays are now released in preparation for their control of the next selection.

As indicated by the foregoing description, the

arrangement of this invention is such that each 50- during which brush 22 contacts a conducting segment of commutator 35. This desirable feature follows from the use of transformer 15, the secondary winding l6 of which can deliver to tube l4 only one impulse for each contacting of brush 22 with a conducting segment of commutator 35, 60. no matter how long said contacting continues. This feature is of especial advantage when there is an undesirable slipping of the drive of the selector switch, which might result in a prolonged contacting by brush 22, and the consequent operation of more than one counting relay per single impuse. 'For this reason the invention is an improvement over that disclosed in Patent No. 1,963,761 granted to O. H. Williford, June 19, 1934.

In the foregoing description, itwas assumed that the setting of the register relays, as controlled in the usual manner by the dial impulses, was such that register relay l l was operated and register relays l0, l2 and I3 were not operated. Ti

For this condition, as hereinbefore described, three revertive impulses were sufiicient to satisfy the sender counting relay chain, operating relays I, 8 and 9 in that order.

With othercombinations of operated and nonoperated register relays, as set up under control of various dial impulses, the circuit illustrated functions in a manner similar to that hereinbefore described, except that the number of revertive ground impulses required to satisfy the sender counting relay chain depends upon the register relay combination previously set up for that particular selection, as this setting determines which counting relay winding is first connected in the anode circuit of tube I4.

With no register relays operated, counting relay 9 is connected in the anode circuit of tube I 4 and one revertive impulse from the selector under control, satisfies the sender, operating relay 9. With register relay III operated, and relays I I, I2, and I3 not operated, relay 8 is first connected in the anode circuit of tube I 4. Two revertive impulses satisfy the sender operating relays 8 and 9 .in that order. With only register relay II operated, three revertive impulses are required (as hereinbefore described in detail). Register relays III and II operated require four revertive impulses, operating relays 6, I, B and 9 in that order. With register relay I2 only operated, five revertive pulses are required to operate relays 5, 6, I, B and 9 in that order. With only register relay I3 operated, six impulses are required and operate relays 9, I, 2, 3, 4 and 9 in the order named. The combination of operated relays ID and I3 require seven revertive impulses, operating relays 8, 9, I, 2, 3, 4 and 9 in that order. Operated register relays II and I3 require eight impulses and relays I, 8, 9, I, 2, 3, 4 and 9 operate in the order named. With register relays Ill, II and I3 operated, nine impulses are required and counting relays 6, 7, 8, I], I, 2, 3, 4 and 9 operate in that order. Register relays I2 and I3 operated require ten revertive ground impulses from the selector, operating the full counting relay chain in the following order: 5,6, 7, 8, 0, I, 2, 3, 4 and 9.

The foregoing description is for the case where the transformer I 5 and resistance I 3 only are used. For some situations it is desirable that there also be used a stepping relay I9 with contacts connected locally to transformer I5. A description of the functioning of this invention when said stepping relay is used will now be given.

In some cases, where the fundamental circuit is long it is found that with the central oflice battery voltages available it is not feasible to induce sufficient voltage in secondary Winding I6 of transformer I5, due to the application of ground by selector brush 22, as hereinbefore described, to effect the ionization of tube It, when the fundamental circuit is connected directly to transformer I5. Under this condition the use of a stepping relay I9, enables a local source of current to be applied to the winding I? of transformer I5. Current through the winding of reiay I9 is supplied from the selector circuit over conductors 3t! and 42, joined respectively to conductors 38 and 39. The circuit path is the same as that previously traced for winding I1 of transformer I5 and resistance I8, excepting that the winding of relay I9 now closes the fundam ntal circuit at the sender. Relay I9 in operating connects round to winding I? of transformer I5 over conductor 39, the circuit to battery being completed 'over' conductor 37. The windings of transformer .I5 are so comiected in the circuit that the cursaid anode to deionize connect said anode to rent due to the operation of stepping relay 36 causes a potential to be induced in winding I6 of transformer I5 in such a direction as to increase the negative grid bias of tube I4, which accordingly does not ionize. When the stepping relay I9 releases, due to the short-circuiting of the line at the selector, as hereinbefore described in connection with the operation of the invention using transformer I5 and resistance I8 without relay I9, the circuit is opened through winding I1. This induces a potential in secondary winding I6 which causes the circuit to function and operate the various counting relays in the manner hereinbefore described.

Since gaseous discharge tube I l ionizes very rapidly, and since the ionization is dependent upon grid potential change only, the selector circuit may be controlled over greater fundamental circuit loops than hitherto possible.

Furthermore, since only a very short application of ground from the switch commutator is sufiicient to ionize the tube, the selector brush shaft may be advanced at a materially increased speed. An additional advantage is the fact that since the gaseous discharge tube controls the counting relays in response to successive closures of the switch commutator, as contrasted with the present fundamental circuit which depends entirely on an impulse responsive relay to control the associated counting relays in response to successive closures and openings of the switch commutator, a simplified train of counting relays is used, having less than one-half as many relays as heretofore employed.

What is claimed is:

1. In a telephone system, an impulsing device, an impulse responsive device, a control circuit extending from said impulsing device to said responsive device, a gaseous discharge tube at said responsive device having its grid inductively connected with said circuit and normally negatively biased below the ionization potential of said tube, an impulse counting circuit connected to the anode of said tube, means controlled by said impulse device for causing surges of potential through said inductive connection for intermittently rendering the grid of said tube sufficiently less negative to cause said tube to intermittently ionize and produce impulses in said impulse counting circuit, and means in said impulse counting circuit responsive to each impulse to momentarily shunt said impulse counting circuit to deionize said tube.

2. In a telephone system, an impulsing device, an impulse responsive device, a control circuit extending from said impulsing device to said responsive device, a gaseous discharge tube at said responsive device having its grid inductively connected with said circuit and normally negatively biased below the ionization potential of said tube, a train of counting relays, a connection from the anode of said tube through the winding of one of said relays, and means controlled by said impulsing device for causing surges of potential through said inductive connection for intermittently rendering the grid of said tube suificiently less negative to cause said tube to intermittently ionize, said tube upon its first ionization operating said one of said counting relays to lock itself operated, to momentarily shunt said connection to said tube and to then rethe winding of the next succeeding counting relay, succeeding ionizations of said tube causing the similar functioning of succesive counting relays.

cuit to deionize said tube.

3. In a telephone system, a selector switch, a sender, a control circuit extending from said switch to said sender, a control relay at said switch in said control circuit, a gaseous discharge tube at said sender having its grid inductively connected with said circuit and normally negatively biased below the ionization potential of said tube, an impulse counting circuit including the cathode-anode circuit of said tube, means controlled by said control relay for advancing said switch in a selective movement, and means controlled in said selective movement for causing surges of potential through said inductive connection for intermittently rendering the grid of said tube sufliciently less negative to cause said tube to intermittently ionize and produce impulses in said impulse counting circuit.

4. In a telephone system, a selector switch, a sender, a control circuit extending from said switch to said sender, a control relay at said switch in said control circuit, a gaseous discharge tube at said sender having its grid inductively connected with said circuit and normally negatively biased below the ionization potential of said tube, an impulse counting circuit including the cathode-anode circuit of said tube, means controlled by said control relay for advancing said 7 switch in a selective movement, means controlled in said selective movement for causing surges of potential through said inductive connection for intermittently rendering the grid of said tube sufliciently less negative to cause said tube to intermittently ionize and produce impulses in said impulse counting circuit, and means in said impulse counting circuit responsive to each impulse to momentarily shunt said impulse counting cir- 5. In a telephone system, a selector switch, a sender, a control circuit extending from said switch, to said sender, a control relay at said switch in said control circuit, a gaseous discharge tube at said sender having its grid inductively connected with said circuit and normally negatively biased below the ionization potential of said tube, a train of counting relays, means for establishing an impulse circuit from a source of positive potential through the winding of one of said relays to the anode of said tube, means controlled by said control relay for advancing said switch in a selective movement, and means con trolled in said selective movement for causing surges of potential through said inductive connection for intermittently rendering the grid of said tube sufficiently less negative to cause said tube to intermittently ionize, said tube upon its first 5 ionization operating said one of said counting relays to lock itself operated, to momentarily connect a source of negative potential in shunt of said source of positive potential to the anode of said tube to deionize said tube and to then con- 10 nect said source of positive potential to the anode through the winding of the next succeeding counting relay, succeeding ionizations of said tube causing the similar functioning of successive counting relays. l5

6. In a telephone system, a selector switch having a control relay and a commutator, a sender for controlling the setting of said switch comprising registering means, impulse counting means and a gaseous discharge tube, a control circuit extending from said sender to said switch, said control circuit having one of its conductors connected through the winding of said control relay to grounded battery and having the other of its conductors connected to ground, a transformer at said sender through the primary winding of which the control circuit is looped, the secondary winding of which is connected between the negative terminal of a source of potential and the grid of said tube whereby said grid is negatively biased below the ionization potential of said tube, said transformer windings being so poled with respect to each other that upon the closure of said control circuit the surge of potential in said secondary winding incident thereto renders said grid more negative, an impulse counting circuit extending from the anode of said tube under the control of said registering means to said impulse counting means, and means controlled by said control relay upon the closure of said control circuit to advance said switch in a setting movement whereby said commutator intermittently short-circuits the primary winding of said transformer causing thereby surges of potential in the secondary winding thereof for rendering the grid of said tube sufficiently less negative to cause said tube to intermittently ionize and upon each ionization to close said impulse counting circuit.

OSCAR MYERS. 

